


Instinct

by blackfin



Category: Voltron: Legendary Defender
Genre: Alternate Universe, Alternate Universe - Canon Divergence, Anal Fingering, Anal Sex, Fluff and Smut, Galra Shiro (Voltron), Kissing, Lovey-Dovey, M/M, Mating Bites, Protectiveness, Rimming, Size Difference, Sweet
Language: English
Status: Completed
Published: 2018-12-23
Updated: 2018-12-23
Packaged: 2019-09-25 06:42:59
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,929
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17116373
Author URL: https://archiveofourown.org/users/blackfin/pseuds/blackfin
Summary: Keith often has a little trouble with the other members of the Blades - half Galra, half human getting accepted into their ranks then almost immediately becoming Shiro's, the Blades' most valuable fighter, mate - but it's alright. There's a very big Galra always looking out for him, after all.





	Instinct

**Author's Note:**

> Inspired by jotakorium's Galra!Shiro design over on Twitter!   
> I absolutely fell in love and just had to write something for it! Originally, I just wanted to write Shiro picking Keith up and things just kind of spiraled out of control from there, as they usually do  
> I would love to flesh this out into a full length fic...so I might just do that   
> Anyway! Please go check out jotakorium's art, it's incredible!! Galra Shiro is just so gorgeous <333   
> Also posted on my tumblr (blackfen) and my twitter (tenebrisfen) <333   
> Thank you!!!

Okay, so…he might have gotten himself into a touch of trouble. 

Arms crossed over his chest, staring defiantly up at the stupidly huge Galra standing before him, blocking his way, Keith considered the fact that right now might be the best time to hold his sharp tongue but the issue with that was the moron in front of him. Some probably considered it a weakness but when faced with such utter arrogant stupidity, he just couldn’t hold himself back. Even when said stupidity was coming from a Galra that was so much bigger than him…and had sharp claws, and a sword…and two cronies standing behind him, both of whom looked as ready to throw down as the main dude. 

Shifting his weight from one foot to another, Keith repeated, “Get out of my way. I’ve got stuff to do.” 

“Little runt like you throwing around orders really pisses me off.” The massive Galra sneered, his upper lip curling in disgust, “You think that just because you’ve been paired with one our best that you can around here like you own the place.” 

Keith rolled his eyes so hard that they nearly popped straight out of his head. Yes, that was exactly what was happening right now, and totally not that this idiot had decided to stop him out of nowhere, for no apparent reason other than to shit talk, when he was just trying to do what he’d been fucking told to. Blowing out a hard breath through his nose, tapping one finger rapidly against his bicep, Keith replied in a cold, curt tone, “I don’t have time for this. Move, or I’ll make you move.” 

“Ooh, hear that?” One of the cronies behind the main guy crowed, nudging his buddy, “He’s going to make us move?” 

“How you think you’re going to do that, small fry?” The massive Galra in front asked mockingly, bending down considerably so that he and Keith were at eye level with one another. It would’ve been easy at that point to sucker punch him, just ram his closed fist directly into that snout but Keith, somehow, restrained himself. He already wasn’t well liked – getting into a fist fight with one of his “comrades” wouldn’t help things. No, he was going to need to get crafty. Maybe use some fancy footwork to just get them off balance. A little bit of humiliation at being taken down without any blows thrown might do these idiots some good as well. 

With that decided, Keith got ready to put his plan into action. Quickly taking note of his surroundings, finding the best way to proceed (that, hopefully, wouldn’t end in violence), it didn’t take him long to realize he was going to need to move quick. The massive Galra was already anticipating a fight. Rearing back, already raising one large, clawed hand with the obvious intent to crash it down onto Keith’s head, he was either making no attempt to hide how much he was telegraphing each movement or didn’t realize just how much he was. Either way, it gave Keith just the kind of opening he needed. 

However, just as he was about to dash forward, meaning to get right under the massive Galra’s arm, push him while he was off balance then figure out something for the other two, a familiar voice called out from behind him, causing him to freeze in mid-step. 

“What’s going on here?” 

He didn’t need to turn to know who it was. Sighing softly, relaxing the tension in his body, Keith waited, tilting his head back slightly to stare passively up at the massive Galra, who was watching the approaching speaker with a ferocious snarl stretched across his ugly face. Couple seconds passed, then he sensed, rather than felt someone come up behind him. He expected, as usual, for a large, heavy, clawed hand to land on his shoulder, gently pulling him backwards into a sturdy, muscular body since that was what Shiro usually did whenever one of their “comrades” was getting a little too rowdy, which was often, unfortunately. So, he was a tad bit surprised when, instead of that, a muscular arm wrapped abruptly around his waist. Lifted up into the air, his legs dangling uselessly, the tips of his toes not even coming close to brushing the floor, Keith couldn’t help but to let out a startled sputter. 

Gawking, too surprised to be offended, Keith craned his head around to stare up at Shiro but he was glaring down at the other Galra, thick brows lowered over glowering eyes. Turning slightly so that Keith was moved just a bit further away, he demanded coldly, “I asked you a question. What is going on here?” 

Apparently, now that Shiro was much closer, the massive Galra, who didn’t look that massive anymore in comparison to Shiro, who towered over him, overwhelming him in height and muscle mass, wasn’t as ready to be a little shit as he had been before. Still snarling just a little bit, he scoffed, shrugged one shoulder and mumbled angrily, “Just messing around. Didn’t mean any harm.”

“Is that so?” Shiro replied flatly, “Because it looked as though you were ready to strike my mate, Dhav.” 

Flushing darkly at the mention of the word ‘mate’, Keith covered his face with one hand. Yes, okay, technically correct…well, not even technically, it was correct, that was the right terminology to use for what he was but he didn’t have to go around announcing it! Scrubbing his face lightly, Keith jumped a little when Shiro leaned down, catching his dangling legs and gathering him up in his arms, carrying him very much like a husband would cradle his bride as they were stepping over the threshold into the home they’d now be sharing together. If this was happening in any other scenario, he definitely would’ve enjoyed it – smooshed to Shiro’s warm, beefy chest, what’s not to love? – but right now, he really just wanted to be put down. 

The Galra who he assumed was called Dhav’s mouth worked furiously. Curling his hands into loose fists, he said tersely, “Perhaps it’s because your mate doesn’t know when to keep his mouth shut.” 

Yep, wrong answer. The side of Shiro’s mouth twitched violently. Sucking in a deep breath, the expression on his face becoming strangely blank, he said coolly, “I’d advise that you think very hard about whether you want to continue down that path, Dhav. You should consider yourself lucky that I’ve restrained myself up to this point, despite the threat you’ve leveled against Keith. Piece of friendly advice: do not push me any further, unless you’d also like to know what it’s like to lose an arm.” 

Truthfully, he fully expected Dhav to go head to head with Shiro. In fact, he was kind of hoping for it. He would have loved to see just how quickly Dhav would have gone down. Unfortunately, there did seem to be one working brain cell in the idiot’s tiny, insignificant brain. With a soft growl, Dhav shot him one last scathing look before sharply turning on his heel and stomping away, closely followed by his two cronies, both of whom did not look at all like they wanted to go up against Shiro. Keith watched after them until Shiro turned as well, and started heading back towards their shared quarters. Tilting his head back, staring up at the ceiling, he wondered how long it’d be before the story started circulating: golden boy Shiro, the strongest and best fighter out of all the Blades, rushing in to save his mate, thereby providing even more evidence, to some, that he shouldn’t be here. 

Sighing heavily, he asked, “What’s the likelihood of you putting me down?”

“Right now?” Shiro asked softly in return, turning down the hallway that lead to their quarters. “None.” 

“I could have handled it.” Keith said, not bothering to hide his irritation. 

“I know.” Shiro said, then added quietly after a moment, “I’m sorry. Whenever I see you in danger, I stop thinking. The only thing that matters is keeping you safe.” 

He sighed again, feeling a little bad for being irritated because honestly? If Shiro was in a similar position, Keith knew he would have done the same without really pausing to think about the consequences. Even the thought of Shiro being threatened or in danger made his heart lurch unpleasantly. Relaxing into Shiro’s hold, reaching up to lightly stroke behind one of his big, fluffy, pointed ears, a small smile tugged at the corners of his lips when Shiro leaned into his touch, eyes fluttering closed as he made a sound that reminded Keith of a cat purring. 

“Thanks for the save.” Keith said quietly, “I’m sorry to have worried you.” 

“Don’t worry about it.” Shiro mumbled, leaning down to give him a quick kiss as he stopped in front of the door leading to their quarters. Cradling Keith close with one arm, he punched in the code into the nearby keypad, then slipped in when the door whooshed open. Small, though it was massive in comparison to what the other members of the Blades had, sparsely furnished with more weapons, tools, and random bits of technology than furniture. Nothing much, but it was his and Shiro’s – a little private space where they could just be together. That alone made it an incredibly special place for him. 

Striding over to the bed, Shiro gently placed him down on top of it, then climbed up beside him. Tugging Keith close, wrapping his much bigger body around him, Shiro squeezed him to his chest, one large hand gently stroking his hair. Tucking his head underneath Shiro’s chin, Keith was content to just snuggle for a little bit, basking in Shiro’s scent and warmth, the irritation and tension of that little spat fading away. Sure, he was going to have to deal with even more looks and snickers when he did finally venture out into the occupied spaces but it wasn’t like he wasn’t used to dealing with that sort of thing. 

Not even three days after being initiated into the Blades, a move that so many within the ranks already disagreed with – a half Galra, half human mutt, it was a disgrace, according to some – he was chosen by Shiro, who half the goddamn Blades were already murmuring would take over when Kolivan stepped down (if that ever happened), chose him not only to be his partner, but his mate. He was happy, he was incredibly happy, even. Shiro was…his everything. It was so fucking sappy but it was true. The moment they’d met, Keith had known. This was someone he’d destroy the entire universe for. He’d follow this Galra into a fucking black hole if need be. While it had, of course, been a little startling to suddenly have Shiro appear before him, sitting all formal like on the floor, looking so solemn and serious that Keith was near convinced that he was about to be booted from the Blades, only to be asked for him to be his mate. 

He had accepted. Even though, by that point, he and Shiro had only known each other for a couple months, having met a short while before he joined the Blades' ranks, he accepted without hesitation. They became mates, deeply connected, and he finally got the family he had always longed for. But oh, had that sent the tongues a-wagging. Keith hadn’t been able to shake the rumors, the insults openly whispered as he passed, even after he’d proved himself again and again. Honestly, he’d probably never be able to completely escape that kind of thing so why even bother being upset about it? No use crying over milk he hadn’t split. 

Still…didn’t stop it from being irritating. Shaking his head slightly, not wanting to linger on that while he and Shiro had some alone time, which was about as rare as Kolivan cracking a smile, Keith decided to make the best of it. Rolling over onto his other side, he slid over to the side of the bed, grabbed the massive bottle of lube out of the box on the floor beside the bed then, after handing the bottle to Shiro, who immediately flushed brightly at the immediate realization of what Keith was doing, set about trying to squirm out of his skintight suit – the process made that more difficult by the fact that he refused to actually get up to do so. 

He struggled for a few moments before Shiro, who wasn’t really know for his patience when it came to this sort of thing, sat up, grabbed the seat of his suit and yanked backwards, ripping the thin material to shreds, fully exposing his ass. Pausing, Keith gave him his best ‘really? Did you need to do that?’ look, since that was the fifth suit he had ruined in the past month, then sighed in an over-exaggerated fashion, his heart already beginning to race, heat pooling into his cheeks, when Shiro didn’t even look away from his ass. Taking a plush cheek into each hand, he spread him open, making him shudder and moan softly, wiggling his hips enticingly, then leaned down to press a hot, wet tongue against his twitching hole. 

From there, things escalated quickly, as usual. Writhing atop the covers, gripping tightly onto one of the pillows, his cock rock hard and dribbling fluids all over the thin blanket, Keith ground back against Shiro, a violent shudder wracking his body when he pushed that talented tongue into his ass, slipping past the tight ring of muscles to playfully tease his sensitive insides. Not bothering to hold back his moans, hardly caring if anyone heard, he let himself enjoy the sensation of Shiro’s tongue inside of him, the wet heat slowly sinking into him, for a little while before moaning in a very specific way that was meant to let Shiro know he was done with teasing, he wanted the actual thing. 

Immediately getting the hint, Shiro pulled back, his handsome face flushed, eyes heavy lidded and burning with lusting want. Grabbing the bottle of lube, he poured a considerable amount out onto his prosthetic hand since the other one hand claws and claws plus any kind of body orifices didn’t really match that well. Rolling over onto his back, he slipped one hand underneath each knee, pulling his legs up and open to give Shiro better access. Shivering with excitement when Shiro’s smooth, lube coated fingers touched his ass, Keith kept his eyes on his mate’s face as he pushed one large finger in. Unsurprisingly, it slipped in easily, as it always did. 

Rolling his hips slightly, grinding down against Shiro’s finger, Keith shuddered and moaned when he added another, thrusting slowly in and out. Little bolts of pleasure raced through his nerves. There was a pool of precum already forming on his stomach. Panting softly, his body burning with pleasant heat, the tips of his fingers and toes tingling, a golden haze settling over his mind, Keith restrained himself from voicing his impatience. While Shiro’s fingers felt amazing, there was something else he wanted even more. Unashamedly looking down at Shiro’s crotch, his heart leaping up into his throat at the sight of the very large, very prominent bulge between his muscular thighs, Keith hungrily licked his lips. There was no point in asking Shiro to hurry – even though Keith was more than accustomed to taking that gorgeous cock, the one thing Shiro would never rush was getting him prepped. 

Pushing in a third finger then a forth, both of which slipped in easily, Shiro spent a short while longer really making sure that he was ready then, finally, after what seemed like an eternity, pulled his fingers out, leaving Keith momentarily mourning their absence. Moving quickly, he got the front of his suit open, letting the beautiful monster that had once been restrained pop free. As always, just the sight of it made Keith’s mouth water. When he first saw it, he’d been…well, admittedly, a lot of afraid. It was massive, a real monster of a cock. Not that he really expected anything else, considering just how big Shiro was but just how big it was had caught him off guard. Completely smooth, colored a deep purple hue, with thick, prominent veins running like highways running all over the circumference, the head was about the size of his clenched fist, the shaft was near about the size of his blade and at the base was a large, swollen mass. 

Resting his large hands on Keith’s thighs, pushing his legs open just a bit further, panting hard, fat droplets of sweat rolling down his forehead, Shiro looked up at him with a heated, hazy expression, and asked, “Is-“

“Please,” Keith whimpered, unable to take it anymore – he was so hot, his ass felt so empty, he wanted nothing more than for Shiro to be inside him, to feel that thick mass fucking his ass, “Shiro!” 

Obviously, he didn’t need any more encouragement than that. Growling softly, revealing two rows of sharp teeth (that sent a weird but familiar pulse of cold, dizzy heat echoing throughout the base of his stomach), Shiro pressed the large, hot, hard head of his cock to his wet, slopping wet entrance and thrust forward, pushing past the tight ring of muscles to sink in deep. Back arching up off the bed, his hips bucking uncontrollably, Keith let out a keening cry as his ass practically squealed in delight, hungrily gobbling up every single inch of Shiro’s cock. Pleasure roared through his body, making him feel stupid and giddy. Good, it felt so fucking good! Shiro’s cock was so big, stuffing him so incredibly full that he could cum from just the sensation of it being inside. 

“Shiro!” He cried, “More! More!” 

He didn’t even really need to ask. Pushing forward until the swell of his knot was resting snuggly against his ass, Shiro paused for just a moment, breathing heavily, his hazy gaze focused on Keith’s face, then began to move. Slowly at first, lightly pumping his hips, focusing more on stirring him up, caressing him deep inside, driving him crazy with the incredible pleasure that even the tiniest movement inspired, he gradually picked up the pace as Keith’s moans and cries moved from coherent whimpers to near babbling gasps and sobs. Thrusting his hips in time with Shiro, slamming down onto his cock, trying to drive it in even deeper, Keith gasped sharply when he was suddenly pulled up off the bed. Gracefully spun around, Shiro’s cock never slipping out, so that his back was pressed to Shiro’s chest and he was comfortably tucked into his lap, Keith shuddered violently, his whole body twitching when the sudden shift in position caused Shiro’s cock to push in even deeper. 

Somehow managing not to cum, though he came very close, Keith used the change in position to give himself a little more leverage. Reaching up to wrap his arms around Shiro’s neck, placing his feet on Shiro’s thighs, he bounced up and down, fucking himself on Shiro’s cock as he thrust upwards, pushing in so deeply that he could feel each thrust echoing up into his stomach. Shiro’s hands remained wrapped tightly around his thighs, the tips of his claws nearly touching, steadying Keith as he moved. 

“Cute-!” Shiro gasped into his ear, nipping lightly at the lobe, “You’re so cute, Keith! I love-!” 

Panting out Shiro’s name in what could have been a prayer or a chant, feeling himself getting closer and closer to cumming, knowing that he wasn’t going to be able to hang on for much longer and, judging by the erratic pace of Shiro’s breathing, as well as the frantic increase of his thrusts, Shiro wasn’t going to last much longer either, Keith slammed his hips down hard, hoping to be able to slip that knot inside of him to give him that one last little oomph but instead of that little dream becoming a reality, Shiro abruptly jerked down, sliding his mouth open and chomped down hard onto Keith’s shoulder. The material of his suit prevented Shiro’s teeth from puncturing his skin but couldn’t stop the rush of ecstasy that came from the sensation of Shiro’s sharp teeth biting down onto him. 

Crying out loudly, throwing his head back as his spine arched practically into a U-shape, Keith came, jizz splattering all over the covers. Slamming his hips down in spastic thrusts, hardly even able to feel Shiro cumming inside him, flooding his insides with copious amounts of scalding hot cum, pleasure short circuiting every single nerve in his body until he felt almost numb, Keith panted shallowly, slumping in Shiro’s hold, content and exhausted. 

“I’ve told you,” Shiro breathed, slowly sliding Keith off his steadily softening cock, causing him to whimper in disappointment, “to not try to take my knot.” 

“One day.” Keith mumbled, raising one fist to shake weakly, “One day!” 

He heard Shiro snort in disbelief, then a warm pair of lips were pressed against his forehead in a soft, sweet kiss. Calloused fingers brushed sweaty hair from his forehead, “You okay?” 

“Better than okay.” Keith yawned, snuggling back against Shiro’s much bigger form. A large hand gently took hold of his chin, turning his head to the side before tilting it back so that Shiro could lean down to kiss him. Sighing contentedly, Keith slowly spun around, moving his lips against Shiro’s, adoring how smooth and firm they were, wrapping his arms loosely around his broad shoulders. 

“You want to take a bath then see if we can actually get some sleep before we get sent off onto our next mission?” Shiro asked softly, already sliding off the bed with Keith easily held up at chest level. 

Humming in agreement, not really caring what they did, as long as he got to stay with Shiro, Keith rubbed his cheek against the soft tuft of hair underneath Shiro’s big, pointed, floppy ears, the soft hair against his skin tickling him a little bit, “Sounds good.”

“Are you going to fall asleep in the bath again?” 

“Yep.” Keith replied with a nod, already right on the verge of falling asleep. Not that he was particularly worn out, it was just that whenever he was this comfy, this content, he just couldn’t help but to slip off into slumberland. 

“You’re going to drown one of these days.” Shiro sighed, though there was a hint of amusement in his voice. 

“No, I won’t because you’ll always be there to pull my head above water.” 

He felt Shiro start a little, then the arms wrapped around him tightened. Burying his nose into the messy muss of Keith’s hair, Shiro inhaled deeply, and nodded, “Yeah, I’ll always be there, Keith.”

“I know, Shiro.” Keith mumbled, resting his chin on Shiro’s shoulder, seeing no reason to try to stay awake since it was obvious that he wasn’t even going to make it to the bathroom. “Because I’m not ever going to leave your side.” 

Another kiss was placed onto his temple, followed by Shiro whispering, “I’m so glad, Keith.” Then he was gone, slipped off into sleep, wrapped up in the warmth of his Shiro. The last thought that fluttered across his mind before sleep claimed him was that when he next woke, he’d give Shiro a big ole smooch and let him know just how happy he made him.


End file.
